Systematic decay studies of even-even $132-138$^Nd, $144-158$^Gd, $176-196$^Hg and $192-198$^Pb isotopes

摘要

The alpha and cluster decay properties of the $132-138$^Nd, $144-158$^Gd,$176-196$^Hg and $192-198$^Pb even-even isotopes in the two mass regions A =130-158 and A = 180-198 are analysed using the Coulomb and Proximity PotentialModel. On examining the clusters at corresponding points in the cold valleys(points with same A_2) of the various isotopes of a particular nucleus we findthat at certain mass numbers of the parent nuclei, the clusters emitted aregetting shifted to the next lower atomic number. It is interesting to see thatthe change in clusters appears at those isotopes where a change in shape isoccurring correspondingly. Such a change of clusters with shape change isstudied for the first time in cluster decay. The alpha decay half lives ofthese nuclei are computed and these are compared with the availableexperimental alpha decay data. It is seen that the two are in good agreement.On making a comparison of the alpha half lives of the normal deformed and superdeformed nuclei, it can be seen that the normal deformed $132$^Nd, $176-188$^Hgand $192$^Pb nuclei are found to be better alpha emitters than the superdeformed (in excited state) $134,136$^Nd, $190-196$^Hg and $194$^Pb nuclei. Thecluster decay studies reveal that as the atomic number of the parent nucleiincreases the N \neq Z cluster emissions become equally or more probable thanthe N=Z emissions. On the whole the alpha and cluster emissions are moreprobable from the parents in the heavier mass region (A=180-198) than from theparents in the lighter mass region (A= 130-158). The effect of quadrupole({\beta}_2) and hexadecapole ({\beta}_4) deformations of parent and fragmentson half life times are also studied.